In some situations it is required to pick up soil at one location and transport it to another. In the case of road building for instance, the contour of the ground is changed to form a road by taking the soil from one location and placing it in another. Not only must the soil be removed from one location, it must also be placed in another specific location.
In many situations however, it is only desired to remove the soil from its current location, and the location it is moved to is not critical. Often it is desired to simply spread the removed soil so that it does not interfere with future operations on the land. An example is where ditches are made to drain standing water from ponds on agricultural lands.
Conventional soil moving machines include scrapers and loaders, where a generally horizontal blade is moved at a shallow depth along the ground, lifting soil and moving same into a bucket where it remains until dumped. Scrapers may incorporate a chain elevator to assist in moving the soil into the bucket. Trenchers or ditchers generally move the soil from the trench and pile it beside the trench, although ditchers are also known which spread the soil that is removed. Such soil-spreading ditchers are disclosed in U.S. Pat. No. 3,624,826 to Rogers, U.S. Pat. No. 5,237,761 to Nadeau et al., U.S. Pat. No. 5,113,610 to Liebrecht et al., and U.S. Pat. No. 6,226,903B1 to Erickson.
The ditch cleaning apparatus of Rogers comprises a disc rotating in a substantially vertical plane. The apparatus rides on skids and is designed essentially to clean existing ditches. The ditcher of Nadeau et al. similarly comprises a disc rotating in a substantially vertical plane and having rippers ahead of the disc. The disc of Nadeau et al. disperses the soil loosened by the rippers. The apparatuses of Rogers and Nadeau et al. leave a ditch with a rounded bottom having a radius substantially equal to the radius of the disc.
The apparatus of Liebrecht et al. uses a spinning disc to both cut and spread the soil. The plane of the disc is oriented at a shallow angle of 15-30 degrees above horizontal, and a shallow angle to one side of 10-30 degrees.
The apparatus of Erickson uses a blade to scrape up soil and deposit it onto a spinning disc that has a plane oriented at less than 45 degrees above horizontal. The blade raises the soil onto a pan and then the soil passes over the pan and onto the disc which has an edge that is juxtaposed to a semi-circular cut-out in the pan. The disc rotates at a relatively shallow angle so that the soil is not raised very much before it is thrown off the disc. A beater may be provided above the pan to push the raised soil down onto the disc as it leaves the pan.
U.S. Pat. No. 6,536,140 belonging to Vaags et al is another example of a soil spreading scraper including a blade to scrape up soil and a spinning disc for spreading the cut soil.
In the devices belonging to both to Erickson and Vaags et al., power to rotate the spinning disc is provided through a power takeoff of a towing vehicle to a gearbox having output which is misaligned from the central axis of the spinning disc so that variable angle joints are required in the drive between the output of the gearbox and the disc which affect the smoothness of the fan rotation and thus the operating efficiency thereof.